linux-kernel - Re: [PATCH v1 08/16] perf daemon: Dynamically allocate path to perf

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Message-ID: <CAP-5=fX7_sFV=xGoefpLm_kRMSos7Ec5Df0WwL-k8x6Z4ZKjeg@mail.gmail.com>
Date:   Thu, 25 May 2023 19:40:53 -0700
From:   Ian Rogers <irogers@...gle.com>
To:     Namhyung Kim <namhyung@...nel.org>
Cc:     Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Jiri Olsa <jolsa@...nel.org>,
        Adrian Hunter <adrian.hunter@...el.com>,
        "Masami Hiramatsu (Google)" <mhiramat@...nel.org>,
        "Steven Rostedt (Google)" <rostedt@...dmis.org>,
        Ross Zwisler <zwisler@...omium.org>,
        Leo Yan <leo.yan@...aro.org>,
        Tiezhu Yang <yangtiezhu@...ngson.cn>,
        Yang Jihong <yangjihong1@...wei.com>,
        Andi Kleen <ak@...ux.intel.com>,
        Kan Liang <kan.liang@...ux.intel.com>,
        Ravi Bangoria <ravi.bangoria@....com>,
        Sean Christopherson <seanjc@...gle.com>,
        K Prateek Nayak <kprateek.nayak@....com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        linux-kernel@...r.kernel.org, linux-perf-users@...r.kernel.org
Subject: Re: [PATCH v1 08/16] perf daemon: Dynamically allocate path to perf

On Thu, May 25, 2023 at 12:17 PM Namhyung Kim <namhyung@...nel.org> wrote:
>
> On Thu, May 25, 2023 at 12:12 AM Ian Rogers <irogers@...gle.com> wrote:
> >
> > Avoid a PATH_MAX array in __daemon (the .data section) by dynamically
> > allocating the memory.
> >
> > Signed-off-by: Ian Rogers <irogers@...gle.com>
> > ---
> >  tools/perf/builtin-daemon.c | 15 +++++++++++++--
> >  1 file changed, 13 insertions(+), 2 deletions(-)
> >
> > diff --git a/tools/perf/builtin-daemon.c b/tools/perf/builtin-daemon.c
> > index 34cbe3e959aa..adb5751c3ed0 100644
> > --- a/tools/perf/builtin-daemon.c
> > +++ b/tools/perf/builtin-daemon.c
> > @@ -90,7 +90,7 @@ struct daemon {
> >         char                    *base;
> >         struct list_head         sessions;
> >         FILE                    *out;
> > -       char                     perf[PATH_MAX];
> > +       char                    *perf;
> >         int                      signal_fd;
> >         time_t                   start;
> >  };
> > @@ -1490,6 +1490,15 @@ static int __cmd_ping(struct daemon *daemon, struct option parent_options[],
> >         return send_cmd(daemon, &cmd);
> >  }
> >
> > +static char *set_perf_exe(void)
> > +{
> > +       char path[PATH_MAX];
> > +
> > +       perf_exe(path, sizeof(path));
> > +       __daemon.perf = strdup(path);
> > +       return __daemon.perf;
>
> Then you need to free it somewhere.

For leak sanitizer, if an allocation is reachable from a global then
it isn't considered a leak. I'll address this in v2.

Thanks,
Ian

> Thanks,
> Namhyung
>
>
> > +}
> > +
> >  int cmd_daemon(int argc, const char **argv)
> >  {
> >         struct option daemon_options[] = {
> > @@ -1503,7 +1512,9 @@ int cmd_daemon(int argc, const char **argv)
> >                 OPT_END()
> >         };
> >
> > -       perf_exe(__daemon.perf, sizeof(__daemon.perf));
> > +       if (!set_perf_exe())
> > +               return -ENOMEM;
> > +
> >         __daemon.out = stdout;
> >
> >         argc = parse_options(argc, argv, daemon_options, daemon_usage,
> > --
> > 2.40.1.698.g37aff9b760-goog
> >